Landscaped gardens on the Central waterfront will have to be ripped up twice for construction of road and rail tunnels, a harbour activist has claimed.

Paul Zimmerman said he was told by engineers at the Central reclamation site that a tunnel for the western section of the Central-Wan Chai bypass that was to be built before the site was landscaped had been put on hold.

'They showed us the plans and they informed us that they are certainly not proceeding with any tunnel work for the Central-Wan Chai bypass or any tunnel work for the North Island Line,' he said.

In the latest consultation documents for the proposed new MTR line, which will link the Tung Chung line to Fortress Hill station, the government had suggested the project would not be required until 2016, Mr Zimmerman said.

'But we would expect the landscaping work to be completed by around 2012 at the latest, with a target of 2011,' he said. 'So this would mean that the Central waterfront will remain a construction site for at least six more years than otherwise required.

'They are going to build all the gardens and the buildings on the surface and then, whenever they are ready, they will cut everything up twice to build the tunnels. To subject the Central business district unnecessarily to six years of dust and noise and loss of enjoyment of the waterfront is absurd.'

Mr Zimmerman said the present plan would harm tourism, and called for work on the tunnel box for the bypass and the rail tunnel to start immediately.

The convenor of lobby group Designing Hong Kong, Mr Zimmerman visited the reclamation site last month as part of a delegation from the Harbourfront Enhancement Committee, of which he is a member, to view the works' progress.

Former MTR tunnelling engineer Greg Wong Chak-yan, also a member of the Harbourfront Enhancement Committee, said the bypass tunnel in the Central reclamation should be built on schedule because both the government and objectors wanted the road built as quickly as possible.

'If there is a public consensus, then why delay the road in the Central reclamation area?' he said.

'Why not build it as scheduled and cover it up and then you will have the park and the fountains and trees so that the public can enjoy it. It would also be cheaper to build the tunnel now.'

A spokeswoman for the Transport and Housing Bureau said details of the North Island Line, and the effect its construction would have on the Central reclamation, would be assessed once the project got the go-ahead.